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Known Limitations

Learn about known limitations in this release for MX Series routers.

For the most complete and latest information about known Junos OS defects, use the Juniper Networks online Junos Problem Report Search application.

General Routing

  • The interface hold-down timer cannot be achieved for less than 15 seconds on the MPC11E line card. The interface on MPC11E goes down if the peer link goes down. The downtime is less than 15 seconds. PR1444516

  • Junos OS does not support the IP options for egress firewall attach points. PR1490967

  • In case of SyncE signal loss, DPLL3 goes in to the Holdover state and still the DPLL1/SYNTH1 signal output gets driven to CB. Hence, the CB DPLL gets in to the Locked state because of the INVALID QL. The output of the Current clock status is always taken from CB DPLL state due to which the status gets displayed as Locked. PR1509356

  • On a fully scaled system where all the slices are utilized by different families of CLI filters, if you try to delete one family, and add or change for another family with a higher number of filter terms, which requires either expansion of the filter or creation of a new filter, the Packet Forwarding Engine fails to add the new filter. We get messages out of sequence as the addition or changing the filter is done before deletion of another filter that frees up the slices. PR1512242

  • The LFM might flap during MX-VC ISSU. PR1516744

  • Issuing the help apropos command in the configuration mode causes the mgd process to generate core file. The mgd process comes back up as long as the command does not get issued again and does not generate core file. PR1552191

  • On MX Series, ISSU or upgrade with validate option might fail if there is less disk space in the /var/tmp/ file. Junos OS recommends that you clear out all log files and core files before initiating upgrade with the validate option (when you do not use the no-validate option) or ISSU. You must also clear all unwanted data using the request system storage cleanup command to clean up all unwanted data. You must ensured there is at least 9 GB free space available in the var/tmp file after copying the VMHost package file to the /var/tmp/ file. PR1582554

  • When a packet that triggers ARP resolution hits services, interface style filter on the output creates a session and closes log with incorrect ingress interface. This issue occurs when the first session hits such a filter. PR1597864


  • When upgrade from Junos OS 21.2 release or prior to Junos OS 21.2 release or later, validation and upgrade fails. The upgrading requires the use of the no-validate command. PR1568757

  • While upgrading the image from 21.2T to 21.3DCB, the no-validate command is mandatory for the upgrade command to proceed. PR1586481


  • If the Routing Engines are not all rebooted after a network service configuration change, the rpd process might crash. PR1461468

  • With local reversion in the ON state, there is a possibility of transit router not informing headend of the RSVP disabled link when link flaps more than once. As a work around, remove the local-reversion configuration. PR1576979

Network Management and Monitoring

  • Junos OS has a feature to block or deny all hidden commands. To use the command, configure the set system no-hidden-commands command. However, when you configure the command and commit, Junos OS blocks or denies new netconf/junoscript XML sessions. As a workaround, delete the system no-hidden-commands command and start a new netconf/junoscript sessions. PR1590350

Platform and Infrastructure

  • When you configure 4000 VPLS instance and send bidirectional traffic with 200,000 MACs each side, after clearing the VPLS MAC table, the following error message gets generated:

    There are no functional impact. This error message occurs with a scaled count of more than 1.5L MACs which eventually gets all cleared successfully. PR1575316

  • When the deactivate services rpm and deactivate routing-options rpm-tracking commands are applied together and committed, some of the tracked rpm added routes are not deleted from the routing table. However, the issue cannot be seen if you apply the following steps: Issue cannot be seen using the following steps:

    • Deactivate routing-options rpm-tracking.
    • Commit the configuration to delete all the rpm tracked routes, if the RPM service needs to be deactivated.
    • Deactivate services rpm.
    • Commit.

Routing Protocols

  • Not using the restart routing command after configuring enhanced ip might result in a label inconsistency that causes the device to generate a rpd core file or dump file. PR1577451

Subscriber Access Management

  • Restarting of provisioning micro-service (prov-man) of APM when connected to a BNG or BNGs might result in the inability for APM to re-establish a functional APMi connection with a BNG or BNGs. This is a result of the inability of BNG to detect the loss of the initial connection. The JSD service of BNG has very loose gRPC keep-alive settings, which makes connection loss detection difficult. PR1645910